1. Field of the Invention
The present invention relates to an ink jet recording apparatus provided with an ink supply and recovery mechanism, which is utilized for an image forming apparatus, such as a printer, a facsimile equipment, a copying machine, or the like, and also, relates to an ink container used for such apparatus. More particularly, the invention relates to an ink jet recording apparatus provided with a full line type recording head that uses deaerated ink, and to an ink container used for such apparatus as well.
2. Related Background Art
The ink jet recording apparatus performs image recording, such as printing, by discharging ink from the recording head to allow it to be deposited to a recording medium. It is easier, therefore, to make the recording head compact and record highly precise images at high speeds and lower running costs. Being non-impact type, the apparatus makes a lesser amount of noises, and also, among some other advantages, it makes color image recording easier by use of many colors of ink. Of these apparatuses, the ink jet recording apparatus of full line type, which uses the line type recording head having many numbers of discharge ports arranged in the width direction of a recording medium, makes recording possible at a speed higher still.
As the method for supplying ink to a recording head of the kind, it is often practiced to adopt a method in which a container of a large capacity is installed integrally with the main body of a recording apparatus together with the ink flow paths, such as tubes, formed between the container and the head cartridge, as well as the mechanism provided for the ink flow paths to carry ink to the head cartridge in consideration of the event that recording may be performed on a large-sized recording medium or liquid should be replenished when the container is installed on the apparatus whose recording volume is great, and then, ink is replenished by means of the mechanism thus provided.
The present inventor has disclosed the structure in the specification of Japanese Patent Application Laid-Open No. 10-6521 wherein a sub-container is arranged to supply liquid to the downstream side by introducing the air while provisionally retaining liquid in the intermediate portion of the liquid supply route, and also, disclosed in the same specification the replenishing method wherein the sub-container is arranged to be a closed space having the reduced pressure in it, then, liquid is replenished in the sub-container while reducing the inner pressure thereof. In accordance with this method, negative pressure generating means can be arranged for the route different from the liquid supply route in order to reduce the inner pressure of the sub-container, hence making it possible to simplify the structure of the liquid supply route. This is an excellent invention that provides the liquid supply system capable of supplying liquid stably without any creation of dust particles when liquid passes the carrying means as compared with the case where the pump or some other liquid carrying means is arranged in the liquid supply route.
In accordance with the invention disclosed in the specification described above, the flow path structure is made simpler for ink supply, and the sub-container thus disclosed in the specification thereof is open to the air outside when liquid is supplied to the recording head. In recent years, however, there has been more demanded on the higher speed recording of more precise images than those conventionally practiced. As a result, the deaerated ink may be used sometimes as one of the methods to obtain the stabilized ink discharges for printing. With the use of the deaerated ink, it becomes possible to prevent bubbles from created in ink unexpectedly. However, since the sub-container is usually open to the air outside, there is a problem that the degree of deaerated condition of ink is lowered as the time elapses.
Also, for the liquid supply from the sub-container to the recording head, the water head difference is utilized or a small ink container is arranged additionally for the recording head unit to provide a capillary force generating member as the one to create the negative force in the interior of such smaller ink container. However, since the sub-container is open to the air outside, there is a need in either case for the provision of suction process by use of a recovery pump to supply ink to each of the nozzles of the recording head of full line type. Then, there is a fear that a considerable amount of ink is exhausted wastefully.
On the other hand, from the viewpoint of using a larger ink container which should be installed on a recording apparatus, it is conventionally practiced to use the ink container provided with an ink bladder laminated with aluminum foil film in consideration of the gas permeability and resistant to shocks. In recent years, however, with the environmental problems which should be dealt with carefully, it has become necessary to provide an ink container which is structured to be easily incinerated for disposition or recycled, while satisfying the condition of the gas permeability and resistance to shocks.